Multiple zone pump and packer apparatus



Dec. 6, 1960 M. B. CONRAD MULTIPLE ZONE PUMP AND PACKER APPARATUS 2 Sheets-Sheet 1 Filed June 11. 1956 viy :0 M

a. M 0 55? t 3 Dec. 6, 1960 M. B. CONRAD MULTIPLE ZONE PUMP AND PACKER APPARATUS 2 Sheets-Shut 2 Filed June 11, 1956 s u 0. x. 4m M W M 9 E 8 V a 5 5 a. &m w 4 B M 0 7 N a 1 0 W n 5 m M Z 7 5 a 4 1 12 1.191 4 7 25 7 8 My 2. Z ZZZ f3: 8 Z3. i. ET? m m T v v NRk K H 7 34ri/C 30, J94, 4/ J/f 9a 31KB 8 ,5 34/ a 5 a. xx flflw aw Wan m 2291 29 a 2 7,. J r h United ta es Patent f MULTIPLE ZONE PUMP AND PACKER APPARATUS Martin B. Conrad, Downey, Calif., assignor to Baker Oil Tools, Inc., Los Angeles, Calif., a corporation of California Filed June 11, 1956, Ser. No. 590,481 14 Claims. 01. 166-118) The present invention relates to subsurface well bore apparatus, and more particularly to apparatus adapted to pump the production from a plurality of longitudinally spaced producing zones in a well bore separately to the top of the hole.

An object of the present invention is to provide improved apparatus for isolating separate producing zones in a well bore and for pumping production from said zones simultaneously and separately to the top of the hole.

- Another object of the invention is to provide apparatus for enabling separate producing zones in a well bore to be pumped simultaneously and separately to the top of the hole, the apparatus including upper and lower spaced packers, in which assurance is had that the upper packer is set in the well casing at a predetermined location above the lower packer, thereby assuring that the pumping units will be appropriately positioned with respect to the separate producing zones.

A further object of the invention is to provide an improved well packer adapted to be anchored in packedolf condition in a well bore.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings: a

Figure 1 is a combined side elevational and longitudinal section through a well packer, with its parts in position for running the packer in a well casing;

Fig. 2 is a view similar to Fig. 1 disclosing the packer anchored in packed-off condition in the well casing;

Fig. 3 is a cross-section taken along the line 3-3'on Fig. 2; a

Fig. 4 is a cross-section taken along the line 44 on Fig. 1;

Fig. 5 is a somewhat diagrammatic longitudinal section through a multiple zone pumping'and well packer apparatus disposed in a well bore.

As disclosed in Fig. 5, a'well bore has been drilled through longitudinally spaced upper and lower producing zones 11, 12 that are to be pumped simultaneously and separately to conduct their respective productions to the top of the well bore. A well casing 13 has been run in the well bore and has been provided with upper and lower perforations 14, 15 opposite the upper and lower producing zones 11, 12, respectively. A suitable cementitious material 16 is deposited behind the well casing between the upper and lower sets of perforations 14, 15

to prevent migration of fluids between the upper and lower producing zones. k

2,953,091 Patented Dec. 6, 1960 ice A suitable well packer or barrier 17 has been anchored in packed-oil condition in the well casing between the upper and lower zones 11, 12. This well packer may be of any suitable form. As an example, it may be a packer such as specifically described in United States Patent No. 2,624,412. As described in such patent, the well packer includes a tubular body 18 having a packing sleeve 19 therearound adapted to effect a seal between the exterior of the body and the wall of the well casing 13. An upper expander 20 coacts with an upper set of slips 21 to anch01 the well packer against upward movement in the well casing, whereas a lower expander 22 coacts with a lower set of slips 23 to anchor the well packer against downward movement in the well casing.

An upper well packer or barrier 24 is also anchored in packed-off condition in the well casing above the upper group of perforations 14. This upper well packer has an outer tubular string 25 secured to its lower portion, which is adapted to extend through the central passage 26 in the lower packer body. The outer string of tubing has a suitable shoulder 27 adapted to rest upon the upper end of the lower packer body 18, to insure the proper longitudinal spacing of the upper packer 24 above the lower packer 17, the lower packer having been set at a predetermined location in the well casing.

The outer tubular string 25 includes a cross-over device 28, described in detail hereinbelow, which will be located substantially opposite the upper set of perforations 14 when the tubing shoulder 27 engages the lower packer body 18. When the lower shoulder engages the packer body, the lower end 29 of the tubing projects through the packer 17 to a point therebelow, the tubing preferably having perforations 30 therethrough to permit the lower zone production 12, flowing through the casing perforations 15, to enter the lower portion 22 of the tubing.

The upper packer 24 includes a lower head orsleeve 31 which is threadedly secured onto the upper end of the intermediate string of tubing 25. This head 31 is slidable on the lower portion of a tubular body or mandrel 32, leakage between the head and body being prevented by a suitable seal ring 33, such as a rubber or rubber-like O-ring, disposed in an internal groove 34 in the head and slidably and sealingly engaging the periphery of the body 32.

Disposed above the sleeve or head 31 are a plurality of circumferentially spaced slips 35 having lower heads 36 slidable in transverse circumferentially spaced grooves 37 in the upper portion of the slidable sleeve. A laterally s'lidable connection is provided between the sleeve 31 and the slips 35 by having oppositely directed tongues 38 on the lower head portions 36 of these slips receivable with- .in' companion opposed side grooves 39 in the sleeve, the sleeve, in turn having inwardly directed portions 40 extending-over the tongues' The tongues 38 and the side grooves 39 are inclined downwardly and outwardly to a slight extent to facilitate expansion and retraction of the slips 35. V

The slips 35 have tapered surfaces 41 that are inclined in a downward and inward direction and which engage companion tapered surfaces 42 on an expander 43 slidably mounted on the body 32 of the upper packer. A positive sliding connection is provided between the slips 35 and the expander 43 by having oppositely directed tongues 44 extending from the sides of each slip fit within companion grooves 45 formed in the'expander. The tongues 44 and grooves 45 extend parallel to the tapered surfaces 42, 41 on the expander 43 and slips 35, the arrangement 'beingsuch that relative movement between the expander and the slips toward each other is required to effect outward expansion of the latter. Until such relative movement can occur, the slips 35 will remain in retracted position.

The upper end of the expander 43 is threadedly secured to a gauge ring 46, the expander and gauge ring both contacting the lower portion of a normally retracted packing sleeve 47, made of rubber or rubber-like material, encompassing the body 32. The upper end of the packing sleeve engages the upper head portion 48 of the body or mandrel and also an upper gauge ring 49 threaded on the head 48. The body head 48 is threadedly secured to a tubular string 50 extending to the top of the hole.

The slips 35 and the packing sleeve 47 are initially or normally in retracted position and are expanded outwardly against the well casing 13 as a result of downward movement of a body 32 within the lower head or sleeve 31. Until such downward movement occurs, expansion of the parts referred to cannot take place. It is desired to prevent such expansion during lowering of the upper well packer 24 in the well casing on the tubular string 50 until the outer or intermediate string of tubing 25 has been piloted through the lower packer 17 with the shoulder 27 on the tubing engaging the lower body 18. It is also desired that a substantial downward force on the tubing string 50 and upper packer body 32 be required before expansion of the upper packing sleeve 47 and slips 35 can occur.

To accomplish the purposes just described, a releasable retainer or latch device is incorporated between the lower portion of the body 32 and the sleeve 31. Thus, the body 32 is provided with a peripheral groove 51 containing a split latch ring 52 which resists contraction. Initially, the split latch ring 52 engages an upwardly facing shoulder 53 on the lower sleeve or head 31, in order to prevent the body 32 from moving downwardly within the lower sleeve 31. The shoulder 53 is inclined or tapered in a downward and inward direction, engaging a companion tapered surface 54 on the ring. When the inclined surfaces 53, 54 are in engagement with each other an upwardly facing shoulder 55 on the body engages a downwardly facing shoulder 56 on the lower sleeve 31, to maintain the body 32 and sleeve 31 releasably secured together against relative longitudinal movement.

It may also be desirable to transmit rotary motion from the tubular string 50 to the body 32 and to the sleeve 31. Accordingly, the body 32 carries a key 57 extending through the split 58 in the ring 52 and slidable within an internal longitudinal keyway 59 in the lower sleeve 31. Such key and keyway connection 57, 59 permits downward movement of the body 32 within the sleeve 31, but causes any rotary motion of the body to be transmitted to the sleeve.

The split latch ring 52 insures that the slips 35 and the packing 47 are maintained in their retracted positions while the apparatus is being lowered in the well casing 13, until the lower portion of the tubing 25 is Shifted down through the lower packer l7 and the tubing shoulder 27 engages the lower packer body 18. When this occurs, further downward movement of the tubing 25 and the slidable head or sleeve 31 cannot occur. Accordingly, the imposition of a suflicient downward force on the tubing string 50 extending to the top of the hole and the upper packer body 32, which for example, may be of the order of 7,000 to 10,000 lbs., will cause the coengaging inclined faces 54, 53 on the ring 52 and sleeve to contact and shift the ring 52 inwardly of its groove 51, the periphery of the ring being disposed within the cylindrical bore of the sleeve 31 below the shoulder 53. The body 32 can now be shifted downwardly, the downward movement being transmitted through its upper head 48 and the packing sleeve 47 to the expander 43. Since the lower sleeve 31 cannot move downwardly, the expander 43 is shifted downwardly in the slips 35, sliding the latter radially outward until their wickers or teeth 65v engage the casing 13 and are embedded in the wall of the latter. When this occurs, the. expander 43cannot move downwardly to any further extent, permitting a continued downward movement of the body 32 to shift the upper head 48 toward the expander 43, the slips 35 and the lower head 31, foreshortening the packing sleeve 47 and expanding it outwardly into firm sealing engagement with the wall of the well casing 13, as well as assuring its sealing against the periphery of the body 32. With respect to the normally retracted packing sleeve 47, the expander 43, slips 35 and lower head 31 may be considered as expander means toward which the head 48 is moved in effecting outward expansion of the packing sleeve. The lower head 31 may also be considered as expander means toward which the head 48 is movable in expanding the normally retracted packing sleeve 47 and the slips 35. The upper packer 24 is now anchored in packed-off condition within the well casing at a predetermined distance above the upper casing perforations 14. Such distance, is predetermined because the distance between the tubing shoulder 27 and the upper packing sleeve 31 is predetermined by the length of the tubing 25 therebetween, in order to place the cross-over device 28 in the casing appropriately with respect to the upper casing performations 14.

Secured to the tubular string 50, by means of which the upper packer 24 and outer tubing string 25 therebelow are lowered in the well bore 10, is an inner tubing string 66 extending through the upper packer 24 and the intermediate tubing string 25 in spaced relation thereto, to provide an annular passage 67 therebetween through which well production from the lower zone 12 can flow in an upward direction, such production passing outwardly through a plurality of ports 68 in the upper packer head 48 into the annulus between the tubing string 50 and the wall of the well casing 13. The lower portion 69 of the inner tubing string is in slidable sealing relation to the body 70 of the cross-over device 28. This body has a central passage 71 therethrough which, in eifect, forms a continuation of the passage through the tubing string 66, and which extends down to the end 19 of the outer tubing string 25. The slidable connection between the inner tubing string 66 and the cross-over body 70 is provided to enable the upper tubing string 50 and the packer body 32 to be lowered with respect to the outer tubing string 25 and sleeve 31, to expand the upper slips 35 and packing 47.

The central passage 71 through the body 70 is adapted to be sealed oit by a packing gland 72, described hereinbelow, in order that the production from the lower zone 12, when entering the lower part of the tubing 25 will flow upwardly through the latter only up to the location of the packing gland 72. Such production is then directed to a longitudinal by-pass passage 73 in the crossover head 70 and into the annulus 67 between the inner and outer tubing strings 66, 25, the lower zone production passing through the upper packer 24 and out through the upper ports 68 into the annulus between the tubing string 50 and the casing 13.

The production entering the casing 13 from the upper producing zone 11 and through the upper perforations 14 passes into a side inlet 74 in the head 70, flowing upwardly through a longitudinal passage 75 that opens to the interior of the inner tubing 66 above the packing gland 72. This production then continues on upwardly through the inner tubing string 66 and into the tubing string 50 that extends to the top of the well bore.

When the upper packer 24, outer string of tubing 25, inner tubing 66, and cross-over device 28 are lowered in the well casing 13 on the tubing string 50, the packing gland 72 is not disposed in the cross-over device. It is after t e inner and outer tubing strings 66, 25 have been properly located in the well casing 13, and the upper packer 24- has been anchored in packed-01f condition in the well casing, that the packing gland 72 together with upper and lower pumping devices 80, 81 are lowered through the tubing strings 50, 66 to their proper loca- 3 tion within the tubing structure. Such pumping'appara f tus includes upper sucker rods 82 which extend through the tubing string 50, 66 to the top of the hole, the lower 'end of such rods being connected to the upper end of a tubing 83 which carries a suitable pumping mechanism 80 of known design. This pumping mechanism includes a piston 84 slidable along the inner wall of the inner tubing 66, the pump also including the usual standing valve 85 and check valve device 86 found in deep well pumps. The lower portion of the pump tubing 83 is telescopically connected to a lower rod 87 which extends through a rod guide 88 of the packing gland which has a rubber or rubber-like packing 89 on its exterior adapted to seal against the wall of the cross-over body 70. The lower rod 87 is connected to the upper end of the tubing 90 of the lower pump device 81, which includes the customary standing valve 91 releasably latched to the tubing 29, the tubing carrying the travelling or check valve 92 and piston 93 forming parts of deep well pumps, the piston 93 being slidable along the inner wall of the lower portion 29 of the tubing 25. The pumping devices 80, 81 are not shown in detail, since they can be of a known design.

The entire pumping mechanism is run down through the tubing string 50 until the rod guide 88 and the packing gland 89 are disposed in appropriate position within the cross-over device 28, as disclosed in Fig. 5. The sucker rods 82, 87 can then be recip'rocated from the top of the hole in the usual manner, the upper rod 82 reciprocating the upper tubing 83 and piston 84. On the upstroke, the tubing 83 engages the lower rod, sliding it in the rod guide 88 and reciprocating the lower piston 93. Thus, both pistons and pumps are reciprocated simultaneously, the lower pump 81 drawing the production from the lower zone 12 through an inlet 94 in tne tubing 90 and discharging it through an outlet 95 into the tubing 25 around the lower rod 87, from where the production flows upwardly around the rod guide 88 into the by-pass passage 73, and then into the annulus 67 between the inner and outer tubings 66, 25, continuing on upwardly through the upper packer 24 and discharging through the ports 68 into the annulus between the casing 13 and the tubing string 50, through which the production will be lifted to the top of the hole. At the same time, the production from the upper zone 11 is flowing into the inlet 74 and through the passage 75 into the inner tubing 66, from where it will pass into the inlet port 96 in the lower pump tubing 83 and through the latter, discharging through its upper port 97 and into the tubing string 66, continuing on up through the tubing string 50 to the top of the hole.

It is evident that by virtue of the packer installation and the pump arrangement described, a single pumping mechanism at the top of the hole can simultaneously reciprocate two pumps in the well bore to pump the production from the lower zone 12 into the tubing-casing annulus above the upper packer 24, for conveyance therethrough to the top of the hole, while the production from the upper Zone 11 is being pumped through the tubing string 50 to the top of the hole. The productions from the upper and lower zones are maintained separate from one another by virtue of the pump ing arrangements just described.

The packer combination insures the proper setting of the upper packer 24 in the well casing with relation to the lower packer 17, to insure that the by-pass device '28 is located in the correct position within the casing.

The upper packer 24 cannot be set in the well casing until the tubing 25 depending therefrom has been appropriately related to the lower packer 17, after which it is only necessary to impose a sufficient downward force on the upper packer to release its retainer or latch ring 52 and then expand the slips 35 and packing sleeve 47 outwardly against the well casing 13. The kev and *keyway connection'57, 58 between the body 32am sleeve 6 31 at the upperpa'cker'need not be used, but it is pro vided in the event the connection effected between the tubing 25 and the lower packer body 18 is a threaded one, requiring rotary motion to efiect a disconnection in the event the upper packer 24 is to be removed from the well casing.

When it is desired to remove the upper packer 24 from the well casing, it is only necessary to elevate the tubing string 50, which will raise the upper head 48, packing sleeve 47 and expander 43, the packing sleeve 47 returning to its normally retracted position. The dovetail connection between the expander 43 and slips 35 causes the latter to retract in the casing. The packer body 32 will move upwardly within the sleeve 31 until the latch ring 52 is again disposed above the sleeve shoulder 53, whereupon the ring 52 expands outwardly into the groove 100 defined between the sleeve shoulders 53, 56, which will then hold the parts in retracted position. The parts will remain in the retracted position until the outer tubular string 25 is again prevented from moving in a downward direction, which will then permit suflicient down'weight to be imposed on the tubing string 50 and the body 32 to release the latch ring 52 and again shift the slips 35 and the packing sleeve 47 outwardly into engagement with the well casing.

The inventor claims:

1. In combination: a tubular running-in string; a body having a connection for securing said body to said tubular running-in string for lowering in a well bore; normally retracted means on said body adapted to be expanded laterally outwardly; expander means relatively slidable on said body below said normally retracted means for expanding said normally retracted means laterally outward in response to downward movement of said body relative to said expander means; and releasable latch means engaging said body and expander means to prevent such downward movement of said body and movable laterally from a latched position to a released position to permit such downward movement in response to a predetermined downward force imposed on said latch means by said body; said latch means being movable from released position to engaged position, following its release, upon upward movement of said body relative to said expander means.

2. In combination: a tubular running-in string; a body having a connection for securing said body to said tubular running-in string for lowering in a well bore; normally retracted means on said body adapted to be expanded laterally outwardly; expander means relatively slidable on said body below said normally retracted means for expanding said normally retracted means laterally outward in response to downward movement of said body relative to said expander means; cam means on said expander means; a split, expansible and contractible latch ring on said body engaging said cam means to prevent such downward movement of said body; said cam means disengaging said latch ring from said cam means to permit such downward movement in response to a predetermined downward force imposed on said latch ring by said body.

3. In combination: a tubular running-in string; a body member having a connection for securing said body member to said tubular running-in string for lowering in a well here; normally retracted means on said body member adapted to be expanded laterally outward; an expander member relatively slidable on said body member below saidnormally retracted-means for expanding said normally retracted means laterally outward in response to downward movement of said body member relative to said expander member; cam means on one of said members; a split, expansible and contractible latch ring on the other of said members engaging said cam means to prevent said downward movement of said body member; said cam means disengaging said latch ring from said cam means to permit said downward movement'in response to. a predetermined downward force imposed on said body member and latch ring.

4. In combination: a tubular running-in string; a body member having a Connection for securing said body member to said tubular running-in string for lowering in a well bore; normally retracted means on said body member adapted to be expanded laterally outward; an expander member relatively slidable on said body member for expanding said normally retracted means laterally outward in response to longitudinal movement of said body member in one direction relative to said expander member; and releasable latch means engaging said body member and expander member to prevent such longitudinal movement of said body and movable laterally from a latched position to a released position to permit such longitudinal movement in response to a predetermined longitudinal force imposed on said latch means by said body member; said latch means being movable from released position to engaged position, following its release, upon longitudinal movement of said body member in the opposite direction relative to said expander member.

5. In combination: a tubular running-in string; a body member having a connection for securing said body member to said tubular running-in string for lowering in a well bore; normally retracted means on said body member adapted to be expanded laterallyoutward; an expander member relatively slidable on said body member for expanding said normally retracted means laterally outward in response to longitudinal movement of said body member relative to said expander member; cam means on said expander member; a split, expansible and contractible latch ring on said body member engaging said cam means to prevent such longitudinal movement of said body member; said cam means disengaging said latch ring from said cam means to permit such longitudinal movement in response to a predetermined longitudinal force imposed on said latch ring by said body member.

6. In combination: a tubular running-in string; a body member having a connection for securing said body member to said tubular running-in string for lowering in a well bore; normally retracted means on said body member adapted to be expanded laterally outward; an expander member relatively slidable on said body member for expanding said normally retracted means laterally outward in response to longitudinal movement of said body member relative to said expander member; cam means on one of said members; a split, expansible and contractible latch ring on the other of said members engaging said cam means to prevent such longitudinal movement of said body member; said cam means disengaging said latch ring from said cam means to permit such longitudinal movement in response to a predetermined longitudinal force imposed on said latch ring by said body member.

7. In a subsurface well tool: a body member adapted to be secured to a running-in string for lowering in a well bore; normally retracted slips on said body member adapted to be expanded laterally outward to anchor said body member against downward movement in the well bore; expander means engaging said slips to expand said slips laterally outward; an expander member relatively slidable on said body member below said slips for efiecting relative movement between said slips and expander means to expand said slips laterally outward in response to downward movement of said body member relative to said expander member; and releasable latch means engaging said body member and expander member to prevent such downward movement of said body member and movable laterally from a latched position to a released position to permit such downward movement in response to a predetermined downward force imposed on said latch means by said body member; said latch means being movable from released position to engaged position, following its release, upon upward movement of said body member relative to said expander member.

8. ;In asubsurface well 1001: a body member adapted to be secured to a running-in string for lowering in a well bore; an expander on said body member; slips on said body member engageable with said expander to be expanded laterally outward to prevent downward movement of said body member in the well bore; a slip moving member relatively slidable on said body member below said slips for expanding said slips laterally outward in response to downward movement of said body member and expander relative to said slip moving member; cam means on said slip moving member; a split, expansible and contractible latch ring on said body member engageable with said cam means to prevent such downward movement of said body member; said cam means disengaging said latch ring from said cam means to permit said downward movement in response to a predetermined force imposed on said latch ring by said body member.

9. In a subsurface well tool: a body member adapted to be secured to a running-in string for lowering in a Well bore; normally retracted slips on said body member adapted to be expanded laterally outwardly; expander means engaging said slips to expand said slips laterally outwardly; an expander member relatively slidable on said body member below said normally retracted slips for effecting relative movement between said slips and expander means to expand said normally retracted slips laterally outward in response to downward movement of said body member relative to said expander member; cam means on one of said members; a split, expansible and contractible latch ring on the other of said members engaging said cam means to prevent such downward movement of said body member; said cam means disengaging said latch ring from said cam means to permit said downward movement in response to a predetermined downward force imposed on said body member and latch ring.

10. In subsur ace well apparatus for use in a well bore having upper and lower producing zones: well casing in the well bore having upper and lower openings communicating with said upper and lower zones, respectively; a lowerbarrier set in the well casing between said upper and lower openings; an upper barrier adapted to be set in the well casing above said upper opening; a tubular string; said upper barrier including a body having a connection for securing said body to said tubular string for lowering in the well casing, normally retracted means on said body expandible against the well casing, an expander member relatively slidable on said body below said normally retracted means for expanding said normally retracted means against the casing in response to downward movement of the tubular string and said body relative to said expander member, releasable latch means engaging said body and expander member to prevent said downward movement of said body and movable laterally from a latched position to a released position to permit said downward movement in response to a predetermined downward force imposed on said latch means by said body; said latch means being movable from released position to engaged position, following its release, upon upward movement of said body relative to said expander member; and tubular means secured to said expander member and engaging said lower barrier to prevent downward movement of said expander member.

11. In subsurface well apparatus as defined in claim 10; wherein said tubular means includes first passage means for conducting fluid from said lower zone and lower casing opening through said lower and upper barriers for discharge into the annulus around the tubular string above said upper barrier; said tubular means including second passage means for conducting fluid from said upper zone and upper casing opening into said tubular string.

12. In a subsurface well tool: a body adapted to be secured to a running-in string for lowering in a well bore; normally retracted means on said body adapted to be expanded laterally outwardly; expander means relatively slidable onsaid body below said normally retracted means for expanding said normally retracted means laterally outward in response to downward movement of said body relative to said expander means; releasable latch means engaging said body and expander means to prevent such downward movement of said body and movable laterally from a latched position to a released position to permit such downward movement in response to a predetermined downward force imposed on said latch means by said body; said latch means being movable from released position to expanded position, following its release, upon upward movement of said body relative to said expander means; and a slidable spline connection between said body and expander means for transmitting rotary movement therebetween.

13. In combination: a tubular running-in string; a body having a connection for securing said body to said tubular running-in string for lowering in a well bore; normally retracted means on said body adapted to be expanded laterally outwardly; expander means relatively slidable on said body below said normally retracted means for expanding said normally retracted means laterally outward in response to downward movement of said body relative to said expander means; said expander means having an upwardly facing shoulder inclined downwardly and inwardly; said body having a groove; a split, expansible and contractable latch ring in said groove engaging said shoulder to prevent such downward movement of said body; said shoulder forcing said latch ring inwardly of said body groove and from engagement with said shoulder to permit such downward movement in response to a predetermined downward force imposed on said latch ring by said body.

14. In a subsurface well tool: a body member adapted to be secured to a running-in string for lowering in a well bore; an expander on said body member; slips on said body member engageable with said expander to be expanded laterally outward to prevent downward movement of said body member in the well bore; a slip moving member relatively slidable on said body member below said slips for expanding said slips laterally outward in response to downward movement of said body member and expander relative to said slip moving member; said slip moving member having an upwardly facing shoulder inclined downwardly and inwardly; said body member having a groove; a split, expansible and contractable latch ring in said groove engaging said shoulder to prevent such downward movement of said body member; said shoulder forcing said latch ring inwardly of said body member groove and from engagement with said shoulder to permit such downward movement in response to a predetermined downward force imposed on said latch ring by said body member.

References Cited in the file of this patent UNITED STATES PATENTS 530,631 Warner Dec. 11, 1894 925,906 Heeter et al June 22, 1909 1,593,909 Nixon July 27, 1926 1,603,188 Lemmon Oct. 12, 1926 1,686,307 Yerkes et a1 Oct. 2, 1928 1,736,254 Davis Nov. 19, 1929 1,855,914 Hux Apr. 26, 1932 2,021,206 Spang Nov. 19, 1935 2,189,701 Burt et a1 Feb. 6, 1940 2,189,703 Burt et 'al Feb. 6, 1940 2,207,019 Linville July 9, 1940 2,370,929 Barnes Mar. 6, 1945 2,513,869 Hofler July 4, 1950 2,522,825 Hoifer Sept. 19, 1950 2,778,430 Baker Ian. 22, 1957 

